High-speed electromagnetic switch



Feb. 3, 1959 E. J. DlEBoLD 2,872,547

HIGH-SPEED ELECTROMAGNETIC SWITCH Filed May 29. 1957 5 Sheets-Sheet 1 i,li l! 'I' li INVENTOR,

il J1, i f EDWARD J. o/EBOLD.

TTORNEX Feb. 3, 1959 E. DIYEBOLD 2,872,547

HIGH-SPEED ELECTROMAGNETIC SWITCH Filed May 29, 1957 3 Sheets-Sheet 2IIIIIIIIIIIII LAMINATIONS- INVENToR,

EDWARD D/EBULD.

A TTORNE )f Feb. 3, 1959 E. J. DIEBOLD 2,872,547

HIGH-SPEED ELECTROMAGNETIC SWITCH Filed May 29, 1957 3 Sheets-Sheet 3INVENTOR,

EDWARD J. D/EBOLD.

A TTORNE Y United v'States Patent 2,872,547 HIGH-SPEED ELECTROMAGNETICSWITCH Edward J. Diebold, Palos Verdes Estates, Calif., assgnor to theUnited States of America as represented by the Secretary of the ArmyApplication May 29, 1957, 'Serial No. 662,552

6 Claims. (Cl. 2MP-93) 'I'his invention relates to an electro-magneticswitch and more particularly to such a switch which is compact and moreeasily assembled and adjusted than previous electromagnetic switches.

Electromagnetic switches can be described generally as comprising aferro-magnetic and electrically conductive body of small size which ismoved by magnetic forces between fixed magnet poles which also serve aselectrical conductors. Magneti'zation of the poles attracts the movablebody, establishing an electrical circuit between them. Demagnetizationof the magnet poles releases the movable body which is carried away byanother force, thus interrupting the electrical circuit. The electriccurrent flowing through the circuit established by the movable body andthe poles produces the magnetic field which provides the hold-in force;loss of this current releases the body.

Most prior electromagnetic switches having a high current capacity havetended to be bulky, heavy, and unduly complicated. ln many, there are agreat number of loose parts, with fastenings or clamping means requiringmuch space and making the switch unwieldy to work with. The entireswitch is usually made as a unit and adjusted once and for all. Thismakes the switch extremely diflicult to adjust and observe while inoperation.

It is therefore an object of this invention to provide an improvedelectromagnetic switch which, for a given capacity, will be moresatisfactory as to size, weight and simplicity than previouselectromagnetic switches.

It is another object of the invention to provide an electromagneticswitch which is easy to assemble and can be adjusted more accurately,easily, and quickly both before and during operation.

fabricating the switch in two subassembliesv rather than These objectsare achieved in the instant invention by in one assembly as haspreviously been done. One of the subassemblies is a closing magnetstructure consisting of a magnetic core. The clamping means fastened tothis core serves also as one current terminal of the switch. On thisclamping body the closing point of the contact is provided by a closingbuffer clamped to the current conductor by means of a copper clampingplate. The iron core of the closing magnet is surrounded by coils tomagnetize it. When this combination of iron core, coils, conductor,closing buler and clamping plate is made as one assembly, it can be madestructurally solid and operatively simple. All these units are mountedon a body portion made of a material which is relatively heavy andsolid, such as brass.

The other subassembly is also made as solid and as compact as possibleand contains an opening permanent magnet, magnetic laminations toenergize the armature, and a copper conductor to carry the current tothe contact, forming a solid metallic body for this opening magnetstructure. On the solid body there are clamped an opening buffer, abuffer clamp plate, two clamper springs,

a guide spring and a main clamp. All these parts are 7 sandwiched andclamped together by four strong screws 2,872,547 Patented Feb. 3, 1959 vdistance and angle of the opening assembly to the closing assembly.

For a more detailed understanding of the structure and functioning ofthe invention, reference is now made to the accompanying drawingswherein:

Figure 1 shows atop view of the improved electromagnetic switch.

Figure 2 is a section taken on line 1-1 of Fig. 1.

Figure 3 is a section taken on line 2 2 of Fig. l.

Figure 4 is an enlarged side View of the contact structure when theswitch is open.

Figure 5 is an expanded view of the contact assembly.

Figure 6a is a side view of the opening magnet assembly.

Figure 6b is a bottom view of the opening magnet assembly.

Referring now more specifically to the drawings and especially to Figs.1, 2 and 3 thereof, Fig. l is a top view of the assembledelectromagnetic switch, Fig. 2 is a sectional view of Fig. 1 taken online 1-1 thereof and Fig. 3 is a sectional view of Fig. l taken on line2 2 thereof. The closing magnet coils are shown in Figs. l and 2 and aredesignated by the numerals 1 and 2. The body section of the closingmagnet structure, on which the coils and the other elements of theclosing structure are mounted, is made of a suitable conducting heavymaterial such as brass. This body section is composed of two partscalled body halves. These two body halves are best seen in the sectionalview of Fig. 3 and are designated as 3 and 4. The two body halves arejoined by a screw such as shown at 5 and a lock washer 6, suitable holesbeing tapped in the body halves to accept the screw. Each body half hastwo brass body upstanding legs, these being shown at 7 and 8 in Fig. 2and at 8 and 9 in Fig. 3.

Adjacent the upstanding body legs are two insulating spacers 10 and 11and snugly placed between the two insulating spacers is the openingmagnet assembly designated generally by the numeral 12. The contactassembly is shown generally as element 13. The specific features of thecontact assembly and the opening magnet assembly will be describedbelow.

A top insulating plate is shown comprising two sections 14 and 15. Thesections of the top insulating plate are shown attached to the brassupstanding legs by means of screws 16-19. The opening magnet assembly isheld from the top insulating plate by means of two screws 20 and 21which are held constantly under pressure by springs 22 and 23. Thesprings put the screw threads constantly under pressure, preventingpossible play in the threads and any consequent vibration of the openingmagnet assembly. In addition to keeping the permanent magnet assembly inplace, the screws serve as an adjustment for the contact spacing. Thecontact spacing can be observed while the switch is in operation bymeans of mirrors 24 and 25. These two mirrors are inserted in theclosing magnet assembly in suitable slots separating the brass bodyhalves. The slots are milled in the brass body halves when they arefabricated and the mirrors are inserted when the switch is assembled.The purpose and functioning of the mirrors will be more fully explainedhereinafter when the opening magnet assembly is described.

Inner pole pieces for closing magnet coils 1 and 2 are shown at 26 and27. These pole pieces are composed of suitable laminated magneticmaterial. Outer pole pieces are shown at 28 and 29. Elements 30 and 31are sections of laminated ymaterial Vwhich connect Ythe inner and outerpole pieces. A suitable 'air gap 'for the 4inner pole pieces isprovid'ed'as shown at32. Reference numeral 33 designates a hollow space in 'thebody halves for the pole lpieces 26 and 27 and air gap 32. Since Fig. 3is a sectional view, the closing core laminations 30 and 31 are notshown in this figure, but it can be seen from Fig. 2 that thelaminations are .placed in front of and behind the space 33 as seen inFig. 3. ln Fig. 3` are also shown the closing magnet buler 34and theclosing magnet buffer clamp 35. Buffere34 is preferably a straight pieceof nickel-silver spring material whileclamp 35 may be any good conductorsuch as copper. As seen from the figure, buffer 34 and clamp 35 arejoined tobr'ass body half 4 by means of screws 54.

The buife'r 34 and the copper buffer clamp 35 arethe only two ypartswhich are assembled to the closing magnet structure consisting of coils,cores, and brass body halves. The remainder of the necessary parts arelocated on the opening magnet assembly 'which is designated generally asnumeral 12 in the drawings. A more detailed` view of the contactstructure 13 is shown lin Figs. 4 and `Sfthe former showing a schematicside View of the structure with the switch in its open position and thelatter showing an expanded view of the contact assembly. Fig. 4 showsclearly the relation of armature 12 to the laminations y26 and 27. Fig.4 also shows the vvarmature 42 connected by means of the spring guide 37to the upper conductor 36 of the opening magnet assembly. As seen inFig. 4 and also Fig. 5, spring guide 37 is clamped between two damperguides 40 and these elements together with opening buffer clamp 38 andopening buffer 39 are held firmly in place by the armature spring clamp41 which is screwed into the upper conductor 36. YIt is seen from Fig. 4that the movement of armature '42 is limited to a very small travelwhich is approximately equal to the thickness of the spring guide up anddown between the upper and lower magnets. This small amount of travelcauses only low stresses in spring guide 37 and therefore reduces oreliminates fatigue breaks. Opening and closing huers 39 and 34, whilethey could be hat, are Ashown as slightly bent in Fig. 5. The slightbend in the buier plate permits clamping with the clamp in such a waythat it adheres tightly to the magnet and does not vibrate loosely inthe air. it is important to note, however, that the bend as shown inFig. is exaggerated and is actually not as great as therein shown. Thisis also true of the damper guides 40.

A side sectional View of the opening magnet assembly is shown in Fig. 3and it is designated generally as element l2. In this figure can be seenthe opening permanent magnet 43 and opening core laminations 44 ofanysuitable magnetic material to direct the iiux to the armature 4Z. Corelaminations are also shown at 45. Rivets are shown at 46-49. Thepermanent magnet and the laminations are securely riveted together toform one compact assembly.

Side and bottom views of the opening magnet assembly are also shown inFigs. 6a and 6b. The side view is similar to the sectional View of Fig.3. Reference numeral 55 designates a top clamp which contains threadedholes to accept screws and 21. From the bottom View it is seen that fourscrews S053 are used to clamp the Contact assembly to the upperconductor 36. From the bottom View it can also be seen that the springguide 37 is of a triangular shape. The armature 42 is subjected tostrong magnetic fields attracting it from side to side bending it acrossits thin dimension. It is seen that the spring guide itself is used asthe contact element. In order to have a conductor and contact of minimummass, the vcontactsurface-itselfris made large and iiat' to preventdamage due to the impact forces.

As lstated above, the armature moves with a very small travel equal tothe thickness of the spring guide. The amount of travel can be observedby the mirrors 24 and which are built into the closing magnet structureas `described above. When looking into mirrors 24 and 25 from above foradjustment of the contact spacing, the picture observed appears similarto Fig. 4 and by comparing the amount'of travel of the armature to thethickness of the spring guide, the travel can be easily adjusted to`have the same magnitude. The contact spacing can be changed byadjusting the screws Ztl and 2l. Itis also important in operation thatthe armature travel parallel to itself, "i. Vejthat the closing bufferand the guide spring hit upon the whole surface at once and not more onone corner than another. The adjustment provided by the screws 2li and21 permits this to be done accurately during operation.

The operation of the switch is as follows: When coils 1 and 2 areenergized, armature 42 is attracted to the closing coil pole pieces 26and 27 and contact is made between buler 34 and spring guide 37, thuscompleting the switch circuit. When coils l and 2 are'deenergized,

armature 42'is attracted by the flux of the permanent magnet 43, thusopening the circuit.

The switch described is a high-speed type, adapted to operate primarilyin rectifier and inverter circuits, which contact of the switch is madeand broken at a high rate. A most serious problem heretofore encounteredin high-speed electromagnetic switches used in these circuits is that ofbounce, i. e., the tendency of the switch contacts, when operating at ahigh rate of speed, to vibrate in the open or closed position, thuscausing faulty operation of the circuit in which the switch is used andalso serious damage Vto the contacts. The electromagnetic switch of theinstant invention has eliminated this problem due to the simplearrangement utilized whereby the contact operates between two metallicspring guide buiers which are clamped upon the magnets which attract thearmature. `Apparently the shock of the spring guide upon the bufferplate is transmitted to the magnet and the buer plate bounces togetherwith the contact plate. Thus, the bouncing between contact surfaces iscompletely eliminated.

Any undue stresses on spring guide 37 due to high speed operation areeliminated by the use of the dampers 40. Y A previously described, theseare simple, straight spring blades which reduce the stress on theclamping point of the guide spring and also reduce random vibrations ofthe guide spring and introduce an element of friction which isbeneficial to dampen Wild oscillations.

ObviouslyV many modifications and variations of the present inventionare possible in the light of the above teachings. It is therefore to beunderstood, that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

l. A structurally solid and compact electromagnetic switch containing aclosing magnet subassembly, a rigid body member and an opening magnetsubassembly, said closing magnet subassembly comprising closing core andcoils and the closing terminal of the switch, said closing core, coilsand terminal all mounted on said rigid body member, said opening magnetsubassembly comprising an opening permanent magnet and poles thereforand the movable terminal of the switch, an armature of magnetic materialcarried by said movable terminal and normally held adjacent the poles ofsaid opening permanent magnet, said opening magnet subassembly beingadapted to tit in a recess provided in the rigid body member, with theclosing terminal and the movable terminal of the switch in operativerelation with each other.

2. A high-speed electromagnetic switch consisting of a closingmagnet'subassembly and an opening magnet subassembly-,said closingmagnet vsubassembly comprising a relatively heavy body portioncontaining two upstandpermanent magnet and clamping means serving asanother current terminal of the switch, a combined movable contact andarmature means held by the latter clamping means, said opening magnetsubassembly being adapted to slide between the upstanding legs of thebody portion of the closing magnet subassembly, with the armature meansbetween said pole pieces and said laminations.

3. A high-speed electromagnetic switch comprising a closing magnetassembly and an opening magnet assembly, said closing magnet assemblycomprising a closing coil with its associated magnetic core and polepieces and a heavy, rigid body portion on which the coil and magneticcore are mounted, said rigid body portion being formed with twoupstanding parallel legs, said opening magnet assembly comprising anopening permanent magnet, magnetic pole pieces and a magnetic armature,said magnetic armature being rigidly attached to one end of a iiat guidespring element, the other end of the guide spring element being rigidlyattached to the opening magnet assembly, said opening magnet assemblybeing adapted to slide between the upstanding legs of the body portion,with the iinal operative position of the two assemblies being such thatthe magnetic armature lies between the respective pole pieces of theclosing and opening magnet assemblies.

4. An opening magnet assembly for a high-speed magnetic switchcomprising a permanent magnet, magnetic lamnations directing the fluxaway from said permanent magnet, a solid metal conductor rigidlyattached to said permanent magnet and said laminations, a contactassembly including an opening magnet buffer, an opening magnet bufferclamp, a guide spring with upper and lower damper elements adjacent tosaid guide spring on upper and lower portions at one end thereof, anopening magnet clamp adapted to rigidly fasten said buffer clamp, guidespring and dampers to said solid metal conductor,

and a magnetic armature rigidly attached to the other end 'l of theguide spring and adapted to be attracted by the flux directed by themagnetic laminations.

5'. A structurally solid and compact electromagnetic switch consistingof a closing magnet subassembly and an opening magnet subassembly, saidclosing magnet subassembly comprising closing core and coils and theclosing terminal of the switch all mounted on a rigid body member, saidopening magnet subassembly comprising an opening permanent magnet andpoles and the opening terminal of the switch, a recess provided in therigid body member, said opening magnet subassembly slideably ttingwithin said recess and being attached to said body member by screwmeans, with the closing terminal and the opening terminal of the switchin operative engagement with each other, the operative relationshipbetween the terminals being adjustable by adjustment of said screwmeans.

6. A contact assembly for a high-speed electromagnetic switchcomprising: an upper electrical contact, a lower electrical contact, arod-like flexible guide spring, said upper electrical contactconstituting one end of said guide spring, a magnetic armature mountedon said one end of said guide spring, an upper damper located above saidguide spring and adjacent thereto on the other end thereof, a lowerdamper located below said guide spring and adjacent thereto on saidother end, an opening buffer, a metal conducting plate, a clamp, saidclamp maintaining in a close fitting relationship said conducting plate,opening buier, upper damper, guide spring and lower damper, a closingbuffer adjacent to and above said lower electrical contact, saidmagnetic armature beingadapted to periodically connect the upper andlower contacts when said armature is periodically energized anddeenergized.

References Cited in the file of this patent UNITED STATES PATENTS Re.24,209 Bernstien Sept. 4, 1956 2,502,811 Willing et al. Apr. 4, 19502,504,101 Reifel Apr. 18, 1950 2,633,488 Brion Mar. 31, 1953 2,675,440Reifel Apr. 13, 1954 2,729,726 Rudd Jan. 3, 1956 2,758,173 Riley Aug. 7,1956

